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Manticore Discrimination Capabilities


PSPR

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That is my impression too. Minelab's refined version of the XY screen, Ferro Check & old White's Spectragraph. All based on conductivity.

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I haven't watched any manticore videos yet.   Still waiting for the operating manual to be released.   I think the target trace screen will be a plus but will it size targets?   tiny looks tiny, medium looks medium?  I'm also really wanting to know if the audio will match the target size....will tiny targets sound tiny?  Will I be able to hear the target's characteristics?   Will a tiny dense target sound dense as compared to something with the same id but less dense.   Probably will only be able to use a DD coil so that will inherently limit fine audio discrimination but maybe they have overcome it.    

Won't know much until I see the manual.

Anyway.....nice to have something new coming out that I'm actually interested in.

HH
Mike

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I have my opinion, but IMO better to hear from someone who knows the Minelab's FBS family.  @steveg has been very helpful explaining that for us Manticore hopefuls.  Maybe we can wake him up 😁 and get some details.  That's not to discourage other knowledgeable responses, though.

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GB_Amateur -- thanks for the kind words!   Yes, you "woke me up," LOL; I saw the notification that you had mentioned my name it a post, so it did indeed grab my attention!

So, I read through this whole thread.  In summary, I'm not sure I have alot to add; Gordiedan said it well, that the 2D screen is NOT "explicity" going to show "shape."  EXPLICITY, the 2D screen reflects a plot of the "bounce" or "variation" in target ID, on successive sweeps.  But, "implicit" in this, is sometimes, SOMETIMES, some sense of "shape." 

In other words, when we "hunt by ear," we often say things like "that target sounds round."  But what are we really saying, when we say that?  What makes us say "it sounds round?"  

The answer of course, is a "short" signal (fast ramp up, or "preamble," then a short-duration target tone, then fast ramp down, or "postable"), along with a consistent ID, and most importantly -- this same consistent ID and "short" signal being CONSISTENT as we repeatedly sweep the coil over the target, and rotate our bodies around the target.  The same "short" sound, with a consistent ID, from all sweep angles, no "variation" in the sound, suggests "round" to us.  And this is EXACTLY what a "round plot" on a 2D screen (at least, on the FBS version of a 2D screen) shows.  It is NOT a "shaping" plot, explicity.  It is essentially a "scatter plot" of multiple "reads" of the ID of the target, over a period of time.  A more "consistent" ID (very little if any variation), calculated over multiple snapshots taken by the machine, will thus show a small, tight, sort of "round" shape.  On the other hand, variation in the ID, over multiple snapshots, will show a more "scattered-out" pattern on the "scatter plot" -- a more "smeared" plot of the ID's, in other words.  Will that "smear" show the "shape" of the target?  Not really, and CERTAINLY not "explicitly."  It's more correct to think of the "shape" plotted on the 2D screen NOT as the "shape of the target," but more as a "scatter plot of all the different ID values the machine is generating over time, of the target under the coil."  The shape is -- explicitly -- just the shape of the plot of the ID values, and NOT -- explicitly -- the shape of the target...BUT...those two ideas can have some "correlation" with each other.  Again -- it's for the same reason that we can "hear" a "round" target.

Hopefully that makes sense, and is somewhat helpful.  Think "scatter plot" of IDs, not explicitly a "sizing/shaping" technology.   

Steve

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18 minutes ago, steveg said:

GB_Amateur -- thanks for the kind words!   Yes, you "woke me up," LOL; I saw the notification that you had mentioned my name it a post, so it did indeed grab my attention!

So, I read through this whole thread.  In summary, I'm not sure I have alot to add; Gordiedan said it well, that the 2D screen is NOT "explicity" going to show "shape."  EXPLICITY, the 2D screen reflects a plot of the "bounce" or "variation" in target ID, on successive sweeps.  But, "implicit" in this, is sometimes, SOMETIMES, some sense of "shape." 

In other words, when we "hunt by ear," we often say things like "that target sounds round."  But what are we really saying, when we say that?  What makes us say "it sounds round?"  

The answer of course, is a "short" signal (fast ramp up, or "preamble," then a short-duration target tone, then fast ramp down, or "postable"), along with a consistent ID, and most importantly -- this same consistent ID and "short" signal being CONSISTENT as we repeatedly sweep the coil over the target, and rotate our bodies around the target.  The same "short" sound, with a consistent ID, from all sweep angles, no "variation" in the sound, suggests "round" to us.  And this is EXACTLY what a "round plot" on a 2D screen (at least, on the FBS version of a 2D screen) shows.  It is NOT a "shaping" plot, explicity.  It is essentially a "scatter plot" of multiple "reads" of the ID of the target, over a period of time.  A more "consistent" ID (very little if any variation), calculated over multiple snapshots taken by the machine, will thus show a small, tight, sort of "round" shape.  On the other hand, variation in the ID, over multiple snapshots, will show a more "scattered-out" pattern on the "scatter plot" -- a more "smeared" plot of the ID's, in other words.  Will that "smear" show the "shape" of the target?  Not really, and CERTAINLY not "explicitly."  It's more correct to think of the "shape" plotted on the 2D screen NOT as the "shape of the target," but more as a "scatter plot of all the different ID values the machine is generating over time, of the target under the coil."  The shape is -- explicitly -- just the shape of the plot of the ID values, and NOT -- explicitly -- the shape of the target...BUT...those two ideas can have some "correlation" with each other.  Again -- it's for the same reason that we can "hear" a "round" target.

Hopefully that makes sense, and is somewhat helpful.  Think "scatter plot" of IDs, not explicitly a "sizing/shaping" technology.   

Steve

Thanks for the explanation, Steve, although most of that was over my aging head!  LOL   Below is a video in a European field with a German guy testing the Manticore with Minelab's chief engineer Lowry walking with him.  There is a lot of information in this video because the camera operator shows the Manticore screen quite well before each item is dug.  If you fast forward to about the 10 minute mark you will see a low conductor that is somewhat oblong on the target trace screen before they dig it.

 

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PSPR -- my apologies for confusing you a bit!

Basically, if a target appears "oblong" on the target trace, it is because the ID values are "variable," and not "consistent."  And it just so happens that often, though not always, "variable" or "bouncing" or "inconsistent" ID values are associated with "non-round" targets, and thus you get a "non-round" target trace.  So, any relationship between target trace shape, and the actual shape of the target, is indirect, and not direct, so to speak.

Steve

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No problem, Steveg.  I tend to get confused easily these days.  LOL  Your shortened explanation makes sense but would mean the Target Trace is only telling the user that an object ID is fluttering which could be deduced just from watching the TID.

I did ask Minelab a question a couple weeks ago about their target trace and if the image generated could be sharpened up in a future software release.  This was the reply I received.

"With experience of using the MANTICORE Target Trace feature it is possible to obtain an implied understanding of the general shape of targets below the coil. From time spent with the machine, our field testers have been able to identify if a target is a long object like a nail or a circular coin shaped object from the Target Trace information displayed on screen. However, it would not be a simple or straight forward task to depict the the exact shape of an object below the coil on the screen, such as making a key in the ground to actually look like a key on the screen. This is because all metal detectors detect the induced electromagnetic field of an object rather than the object itself."

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I'd be curious if a circularly symmetric target (in one axis) will still give a tight dTID plot when that axis is askew of vertical.  An example is a coin on edge.  Again, I have a (educated?) guess but without any experience seeing conductivity vs. ferrous content (ferrocity?  😁) I'm not going to muddy the airwaves with speculation.

From both Minelab's response to PSPR and Lawrie's interpretation in the videos, though, I think it's fair to say that sometimes the assymetry on the plot indicates an assymetric target, but neither the cause nor the effect is guaranteed.  We'll know more in a few months....  🤞

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PSPR -- 

I think what Minelab said to you, i.e. that with target trace, it is possible to obtain an "implied understanding" of the "general shape" of targets under the coil, would be a "fair" way to say it.  That's what I'm trying to say when I say the "shape" is not EXPLICITLY reflective of the target shape, but more "implicit."  There is a relationship, but it is not DIRECT, it's INDIRECT. 

In other words, this is not like a ground-penetrating radar or something like that, where you can actually "see the outline" of the target's shape.  And that is exactly what Minelab said, in the second paragraph of their reply to you.  Instead, target trace is, again, a scatterplot of ID values.  The less "deviance/divergence" in successive calculations of the target ID (i.e. the more consistent the target ID), the more round/small the on-screen plot will appear.  On the other hand, the more "divergent/deviant" the target ID calculations are, the more "elongated" or "smeared" the on-screen plot will appear.   And it JUST SO HAPPENS that most round objects, such as coins or rings, usually have consistent/non-deviating ID -- and hence the scatterplot of a coin's or ring's target ID values would ALSO be "round."  On the other hand, it JUST SO HAPPENS that many trash objects, such as nails, have "divergent/deviant" target ID values, that seem to "bounce all over the place," and thus the scatterplot of a nail's ID values would be more "elongated" in most cases.

HOWEVER, it is highly likely that target-trace plots of OTHER trash targets, such as pull tabs, beaver tails, .22 casings, etc., will ALSO appear small, and basically round (or perhaps very slightly ovaled in shape) -- not that different from a coin.

GB -- 

You said this ... " I think it's fair to say that sometimes the assymmetry on the plot indicates an assymmetric target, but neither the cause nor the effect is guaranteed."

I think that is a very good/accurate way to state it.

***Again, everything I am saying is ASSUMING (though it's an educated/relatively confident assumption) that target trace on the Manticore will be very similar to target trace on the CTX.***

Steve

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On 11/1/2022 at 7:51 AM, PSPR said:

 I mentioned in my introduction post is determining when aluminum, specifically pull tabs or parts of tabs, is under the coil.  In my common hunting grounds pull tabs are common everywhere.

  To eliminate tabs a huge part of the jewelry TID's also must get eliminated. Other than on a beach, if I even had the desire to dig up every pull tab the area would look like a bombing range when I was finished.   I really have no desire to dig up thousands of pull tabs.

So, the question for me is whether the Minelab Manticore is going to be able to identify a pull tab or part of a tab vs. a gold or silver ring? is it going to provide an advantage in identifying the various pull tabs vs. a gold ring.

I'm thinking pull tabs are going to come in with a similar shape to rings and coins on target trace and be of little value distinguishing between the two.  I'll go ahead and order a Manticore as soon as they are released but I'm feeling very disappointed that I'm going to probably not be able to identify pull tabs from jewelry with this machine.

 

You answered your own question in your first post last paragraph. Your only option is to notch out specific types of tabs in the area you are hunting realizing that in doing so you will be missing some gold jewelry...just tell yourself "that could have been a gold ring" every time you pass a target....then every time you dig a pull tab just tell yourself "that could have been a gold ring" and all will be ok. The more you dig the more you find...ask yourself how much time do you want to spend analyzing a little black blob on a screen? It does work both ways however...passing targets can be a good thing but its always at risk..we all take our chances at times. 

strick

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